Methods: We performed pair-wise comparisons of northern distribution limits and range sizes for species with variable versus non-variable coloration.

Conclusions: Species with variable colour patterns had geographic distribution ranges that extended further north and covered much larger areas than those of congeneric species with non-variable colour patterns. Our results are consistent both with the hypothesis that species with variable colour patterns have experienced a faster rate of post-glacial range expansions, and with the competing hypothesis that species of large range that experience divergent selection more readily evolve variable colour patterns.

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